The research proposal centers on the basic action of lead on representative procaryotic and eucaryotic organisms. The study is devoted to defining the primary mechanisms of lead's action at the cellular and subcellular levels as well as the effects of lead on individual cellular chemical components. This proposal contains studies on the effects of lead on depolymerization of membranal RNA and aliphatic ketone biosynthesis to elucidate mechanisms of lead-membrane interactions. Other studies are designed to identify the cellular mechanism(s) which create cellular tolerance to lead and the conditions for the abstraction and then exclusion of lead. These studies are based on surface ion-flux ratios and will include cell electrophoresis, cell wall composition studies, and Mg2 ion uptake measurements. In conjunction with these studies are those on determining gross ultrastructural changes in the cell wall and/or membrane after exposure to lead and the cellular localization of immobilized lead.